DRESDEN, Germany (Reuters) - German police are stepping up protection of Muslim institutions in Dresden after two improvised bombs exploded in the eastern city on Monday evening, one at a mosque and one at an international conference center.

No one was hurt by the blasts although the imam of the mosque was inside the building with his wife and sons.

“Even if we so far have no claim of responsibility, we must go on the basis that the motive was xenophobic,” Horst Kretzschmar, president of Dresden police, said in a statement.

He said police believed there was a link to celebrations planned for the coming weekend in the city to mark the anniversary of German reunification on Oct. 3, 1990.

Kretzschmar said three mosques, a Muslim social center and a prayer room would be given protection immediately.

Soon after the mosque explosion, Dresden’s International Congress Center was also damaged by a home-made device and the bar of a nearby hotel was evacuated.

Mehmet Demirbas, founder of the mosque that was hit, said the Muslim community had been expecting some kind of attack for a long time.

“Glass panes have been broken in the past, or graffiti on the wall. But this is the first time something like this happens. Hopefully it will be the last time and we carry on happily living in Dresden,” he said.

Dresden was the cradle of the anti-Islam PEGIDA grassroots movement whose weekly rallies attracted around 20,000 supporters at the height of its popularity at the start of 2015.

The influx of about 1 million migrants, mostly Muslims, to Germany last year has increased social tensions, especially in eastern Germany where there have been some high-profile attacks on refugee shelters.

Support for the Alternative for Germany (AfD) party, which says Islam is not compatible with the constitution, has risen due to Chancellor Angela Merkel’s open-door refugee policy.

AfD co-leader Frauke Petry condemned the attack on the mosque, saying: “Attacking a building in which people worship God is barbaric, whether it be a church, a mosque or a synagogue.”

German Finance Minister Wolfgang Schaeuble stressed at an annual conference on Islam on Tuesday that Islam belonged to Germany, repeating a view that Merkel voiced in 2015 ahead of a PEGIDA demonstration in Dresden.

Reporting by Reuters TV in Dresden and Thorsten Severin in Berlin; Writing by Madeline Chambers and Michelle Martin; Editing by Catherine Evans